Hydrocarbon conversion



May 25, 1943. B. sELLMr-:YER

mnmormmsow 'coNyERsIon Filed Nov. 30, 1940 Patented May 25, f

Bernardus Sellmeyer, Leonia, N. J., assignor to- The M. W. Kellogg Company, Jersey City, N. J., a corporation of Delaware v Application November so, 1940, serial N6. 361,932

12 Claims. (Cl. 26th-683.4)

This invention relates to the alk'yiatio'n of low t molecular weight paraillnic hydrocarbons with 1 low molecular weight oleflnie hydrocarbons to produce paraiilnic hydrocarbons of higher molecular weight suitable for use as; gasoline motor fuel. More particularly, the invention relates 'to the alkylation of iso'paramnic hydrocarbons such as isobutane with low molecular weight oleilnic hydrocarbons such as butenesand propylene to produce paraillnic hydrocarbons boiling withinV the gasoline boiling range and of high anti-knock value.

Sulfuric acid is employed to catalyze the alkylation of low molecular weight paraillnic hydrocarbons such as isobutane with `butenes and propylene. The raw material ordinarily employed in carrying out such an operation is a mixture of hydrocarbon gases such as those produced by oil cracking operations which contain the desired reactants. 'I'hese gaseous mixtures ordinarily'predominate in paralnic and oleflnic hydrocarbons having three and four carbon atoms per molecule. Such a mixture may be employed as such as fresh feed to the alkylation process, or a selected fraction-may be employed which predominates in (3i-hydrocarbons and contains only a small proportion of C: hydrocarbons. In any event, however, the use of the raw materials which are available for this process involves the introduction into the process of a definite proporpossibly propyiene. It is to be understood. 110W- ever, that the invention is not limited to the speclfic modification illustrated by the drawing but v is capable of other modifications, as will be ap parent to those skilled in the art. Y

In describing the invention by reference to the specific modification illustrated by the drawing reference will be. made to the treatment of a raw material consisting predominantly of hydrocarbons having four .carbon atoms per molecule and containing a minor proportion of C: hydrocarbons. It is to be understood, however, that the invention is not limited to the treatment of a raw material of this description but is aption of low-boilingl hydrocarbons such as propane which are notpsuitable as reactants for the alkylation reaction. 'I'he presence of these hydrocarbons such as propane in the reaction zone is notv in itself harmfulv to the reaction. In the continuous processes which `are ordinarily ernployed, with recycling of isobutane, the presence of a small proportion of these low-boiling hydrocarbons such as propane in the reaction zone may be desirable. However, they tend to accumulate in the system to 'excessive proportions unless measures are taken' for continuous or periodical removal of them from the systemv Itis an object of this invention to provide an alkylation process, employing a fresh feed containing low-boiling hydrocarbons such as propane which areL non-reactive in the alkylation reaction, in which such non-reactive hydrocarbons are eliminated from the system in a novel and eilicient manner.

The invention will be described -by reference .to the accompanying flow diagram which illustrates an application of the invention toa process for the alkylation of isobutane with butenes and plicable to the treatment ofraw materials containing larger proportions of C: and lighter hydrocarbons and also is applicable to the treatment of raw materials 'containing substantial proportions of hydrocarbons having ilve or more carbon atoms per molecule.

Referring to the drawing, the alkylation reaction is carried out in reactor I in which isobuitane.' normal butane, propane, butenes and sulfuric acid are intimately mixed. A mixture of these materials is introduced into reactor I through line 2, and suitable means are provided for effecting intimate mixing of the reactants in reactor I. For example, line 3 provided with pump 4 may be provided for continuously withdrawing a mixture of the reactants, sulfuric acid and liquid products from one portion of the reactor and reintroduclng it at another portion thereof. A portion of the mixture withdrawn from reactor I through line -3 is continuously diverted through line I which connects with separator ,8. Iny separatort the mixture is permitted to separate into an upper layer of alkylate and unreacted gas and a lower layer of acid.

The acid separated in separator t is continu' ously withdrawn through line 2, 'provided with pump'l, and returned to reactor I. A portion of this acid is diverted vfromvline 2 through line l and withdrawn from the fSystem as spent acid. The acid thus'withdrawnthrough line 8 is replaced by fresh acid introduced` to the system through line l, provided with pump I0, which connects with line 2.

'I'he mixture of alkylate and normally gaseous hydrocarbons which separates in the upper por- -tion of separator i is withdrawn continuously through line Ii, provided with pump l2, which connects with isobutane fractionator I3. In fractionator Il conditions oftemperature and pressure are maintained for effecting separation of a condensate in the lower portion thereof containing the alkylate product and normal butane.

. 'I'he mixture of alkylate and normal butane is withdrawn from fractionator I3 through line I4 for further treatment for the recovery of the butane and the gasoline constituents of the alkylate. butane passes overhead and is withdrawn from fractionator I3 through line I5. Line I5 connects with condenser I6 wherein means are provided for effecting condensation of the gas. The condensate thus obtained is withdrawn from condenser I 6 through line I1 provided withpump I8. A portion of this condensate is diverted from line I'I through. line I9; and returned to fractionator I3 as reflux.

Line ,connects with line 2 at a point intermediate the junction of lines 2 and 9 and the entrance of reactor in orderto effect recycling of the isobutane fraction to the reaction.

Reactor I is operated under conditions which permit continuous evaporation of unreacted gases` in order to eiect cooling of the reaction mixture and maintain it at the desired reaction temperature. For example, in effecting alkylation of isobutane with butenes or their dimers or trimers it is desirable to have in reactor I an amount'ofa lighter gas such as propane which will promote vaporization.

The gas mixture thus evaporated in reactor I is withdrawn therefrom throughline I8 provided with a compressor I9 and -cooler 20. By means of compressor I9 and cooler 20 the gases are compressed and substantially condensed. Whether or not all of the gases are condensed depends upon Ithe desired method of operation and on the quantity of light hydrocarbons such as The condensate and propane in -the mixture. any accompanying uncondensed gases are introduced from line I8 into a separator or accumulator 2 I. Condensate collected at 2| is withdrawn therefrom through line 22, provided with a pump 23, and reintroduced into reactor I. L

If substantially all the gases withdrawn from reactor I through line I8 are condensedat I9 and 20 a portion of the condensate in line 22 is diverted therefrom through line 24 provided with pump25. Line 24 connects with a depropanizer fractionator-29. Fractionator 26 is operated under conditions of temperature and pressure to separate as a condensate materials desired as reactants in reactor I and to separate overhead a gas containing a sufficient quantity of propane and other` light hydrocarbons present to "prevent the, accumulation of these gases In the reaction zone to an excessive amount. When operating' at equilibrium conditions the' amount of these gases must equal the amountintroduced with the fresh feed. The gas thus separatedpasses overhead in fractionator 26 and is withdrawn therefrom and from the system through line 21. The .condensate collected in the lower portion of fractionator 29 is withdrawn therefrom through line 28 which connects with line 2 whereby the condensate is recycled to the alkvlation reaction.' e r If a substantial proportion of the gases withdrawn from reactor I through line I8 remains uncondensed after passage through compressor I9 and cooler 20 these uncondensed gases are separated aty 2| and withdrawn therefrom through line 29 whichI connects withl line 24` -whereby the gases are introduced into fractionator v26 for treatment in the -manner def` l7&1181'115hydlfitilrllliilfis plifided by ihe'present DI'O-l A gas fraction predominating in isoscribed above. If depropanizer2l is operated at a higher pressure than separator 2| it willV be desirable to provide a compressor Il in line 29 to effect transfer of the gases to fractionf ator 28.

The fresh feed 4to the' process which, for 'cx" erably if the fresh feed contains more C: hydrocarbons than are desired in reactor the fresh feed may be introduced into fractionator 2l by means of linel 33 which vconnects line 3| with line 24. If the fresh feed isintroduced into the fractionator 26 it is subjected to fraction--A ation in the manner described to separate a oonden'sate containing the proportion of C: hydrocarbons which it is desired to introduce into reactor I. I l

The fresh feed may contain all the isobutane which is consumed in the process, or vall or a portion of this material may be introduced from4 sired fraction of the alkylate may be recycled to the reaction zone.

In reactor I it is preferred to maintain a ratiov of isobutaney to butenes which is greater than 1. For example, the feed to the reactors introduced through line 2 along with the acid may consist, in mol per cent, of 60 to 65 per cent isobutane, 12 to 15 per cent butenes, 18 to 22 per cent normal butane and '2 to 5 percent C:

' hydrocarbons.

Reactor I'is yoperatedpreferably at a pressure not substantiallylgreater than atmospheric,

for example, 5 pounds gauge and at the desired reaction temperature, forl example, 40 F.

'Ihe aikylate an'd butanes are fractionated In fractionator I3 preferably at a suitably higher pressure, for example, 100 to 120 pounds per square in ch.

The gases withdrawn from reactor I through line I8 are compressed to a pressure which will vary depending uponthe amount of C: and lighter hydrocarbons which are contained in the gas. Under ordinary voperations these gases are compressed to a pressure of pounds per square ich or higher.

Depropanizer fracticnator 20 ordinarily is-operated at a substantially higher pressure in order to obtain the desired separation. For example, in this fractionator a pressure of 200 pounds per square inch may be maintained.

Thev invention provides an alkylation process for the treatment of raw materials containing reactions desired for the process and in addition hydrocarbons which are lower boiling than the reactants. In accordance with Kthis process such low-boiling hydrocarbons4 are utilized in the reaction zone to effect the necessary cooling l and are then eliminated from the system in order ,to prevent their? ceumuiation to an undesired degree. I'he method for the elimination of these ess involves the fractionation treatment of a mixture which contains the maximum concentration of these light hydrocarbons, thus reducing to a minimum the apparatusrequirementsof the process and the consumption of energy.

The invention has been described by reference to a speciilc application of it to a specic process.

It is to be understood. however. that the inventaining said reaction zone atalkylation conditions of temperature Iand pressure effective to vaporize unreacted hydrocarbons including said lower boiling hydrocarbons to facilitate maintaining the reactants in the reaction zone at the desired reactiontemperature. withdrawing said vaporized hydrocarbons from said reaction zone, `'cooling said vaporized hydrocarbons externally of said reaction zone to condense at least a portion thereof, reintroducing into said reaction zone as condensate a portion of said cooled hydrocarbons,

introducing another portion of said cooled hydrocarbons into a fractionating zone, maintaining conditions in said fractionating zone effective to separate said last-mentioned `portion of the cooled hydrocarbons into a condensate fraction containing the constituents of said last-men-4 tioned portion of the cooled hydrocarbons which are suitable as reactants in the alkylationreaction and a vapor fraction containing lower boil? ing hydrocarbons unsuitable as reactants for the alkylation reaction, introducing said condensate fraction into said reaction zone, and withdrawing said vapor fraction froml the system.

2. A process,k for alkylating lowmolecular weight paraiilnic hydrocarbons with low molecullar weight oleflnic hydrocarbons to form parafilnic hydrocarbons which comprises (continuously) introducing into an alkylation reaction zone sulfuric acid alkylation catalyst and hydrocarbons comprising low molecular weight hydrocarbons.

, suitable as alkylation reactants and lower boiling hydrocarbons' unsuitable as alkylation reactants, maintaining said reaction z one at alkylation conditions of temperature and pressure effective to vaporize unreacted hydrocarbonsincluding said low-boiling hydrocarbons to facilitate maintaining the reactants\in the reaction zone at the desired reaction temperature, continuouslyI with-, drawing said vaporized Ahydrocarbons yfrom said reaction zone, cooling said vaporized hydrocarbons externally of said reaction zone to condense at least a portion thereof, continuously reintroducing into said reaction zone as condensate a portion of said cooled hydrocarbons, introducing another portion of said cooled hydrocarbons into a fractionating zone, maintaining conditions in said fractionating zone effective to separate said last-.mentioned portion of the cooled hydrocarbons into a condensate ,fraction containing the constituentsmof said last-mentioned portion of the cooled hydrocarbons which are suitable as re-y actants in the alkylation reaction and a vapor.

fraction containing lower boiling l'iydrocarbonsl unsuitable .as reactants for the alkylation reaction, continuously introducing said condensate vfraction into vsaid reaction zone, withdrawing 6 said vapor fraction from the system, and conaction zone a liquid containing the alkylation product. 3. A process for alkylating low molecular 1 0 weight paraiiinic hydrocarbons with low molecular weight oleflnic hydrocarbons to form parafnlc'hydrocarbons which comprises introducing into an alkylation reaction zone sulfuric acid alkylation catalyst and hydrocarbons comprising low molecular weight hydrocarbons suitable as alkylation reactants and lower boiling hydrocarbons unsuitable as alkylation reactants, maintaining said reaction zone at alkylation conditions of temperature and pressure eiective to vapoi'ize unreacted hydrocarbons including said lower boiling hydrocarbons to facilitate maintaining the reactants'in the reaction zone'at the desired reaction temperature, withdrawing said vaporized hydrocarbons from said reaction zone,

cooling said vaporized hydrocarbons externally of said reaction zone to eilfect condensation thereof, relntroducinginto said reaction zone a portion of the condensate thus obtained, introducing another portion of said condensate into a fractionating zone, maintaining conditions in said fractionating zone effective to separate said last-mentioned portion of the condensate into a condensatefraction containing the constituents introduced into said fractionating zone which ar( suitable as reactants in the alkylation reaction and a vapor fraction containing lower boiling hydrocarbons unsuitable as reactants for the alkylation reaction, introducing said condensate fraction into said reaction zone, and withdrawing saidl vapor fraction from the system.

4. A process for alkylating low molecular ular weight oleiinic hydrocarbons .to form paraillnic hydrocarbons which comprises introducing into an alkylation reaction zone sulfuric acid alkylation catalyst and hydrocarbons comprising alkylation reactants and lower boiling hydrocarr' bons unsuitable as alkylation reactants, main- "0 taining said reaction zone at alkylation conditions ofY temperature and'pressure eiective to vaporize unreacted hydrocarbons including'said lower boiling hydrocarbons to facilitate main- E; taining the reactants in' thereaction zone at the 5" desired reaction temperature, withdrawing said vaporized hydrocarbons from said reaction zone, cooling said vaporized hydrocarbons externally of said reaction zone to'condense a portion thereof, introducing into said reaction zone the con- \densate thus obtained, introducing the uncondensed portion of said vaporized hydrocarbons into a fractionating zone, maintaining conditions in said fraction'atlng zone effective to separate hydrocarbons introduced. therein into a condensate fraction containing constituents introduced into said fractionating zone which are suitable as reactants in the alkylation reaction and a vapor fraction containing lower boiling hydroca r- -15`weightlparaiiinic hydrocarbons with -low molectinuously withdrawing from the alkylation reweight parailinic hydrocarbons with low melee-"- low molecular weight hydrocarbons suitable as bons unsuitable as reactants for the alkylation A ular `weight olelnic hydrocarbons to form paraiiinic hydrocarbonsv which comprises introducing into an alkylation reaction zone sulfuric acid alkylation catalyst and hydrocarbons comprising isobutane, propane and olenic hydrocarbons reactive with the isobutane, maintaining said reaction zone at alkylation conditions of temperature and pressure eiective to vaporize unreacted hydrocarbons including propane to facilitate maintaining the reactants in the reaction zone at the desired reaction temperature, withdrawing said vaporized hydrocarbons from said reaction zone, cooling said vaporized hydrocarbons externally of said reaction zone to condense at least a portion thereof, reintroducing into .said reaction zone as condensate a portion of said cooled-hydrocarbons, introducing another portion of said cooled hydrocarbons into a fractionating zone, maintaining conditions in said fractionating zone eective to separate hydrocarbons introduced therein into a condensate fraction containingl the isobutane therein and a vapor fraction containing propane, introducing said condensate taining said reaction zone at alkylation conditions of temperature and pressur'e effective to vaporize unreacted hydrocarbons including said lower boiling hydrocarbons to facilitate maintaining the reactants in the reaction zone at the desired reaction temperature, withdrawing saidLvaporized hydrocarbons from said reaction zone, cooling said vaporized hydrocarbons'externally of said reaction zone to condense at least a portion thereof, reintroducing into said reaction zone `as condensate a portion of said cooled hydrocarbons, introducing another portion of said cooled hydrocarbons into a fractionating zone, maintaining conditions in said fractionating zone effective to separate said last-mentioned portion of the,cooled hydrocarbons into a condensate fraction containing the constituents of said last-mentioned portion of the cooled hydrocarbons which are suitable as reactants in the a'lkylation reaction and a vapor fraction containing lower boiling hydrocarbons unsuitable as reactants for the alkylation reaction, introducing said condensate fraction into said reaction zone, withdrawing said vapor fraction from .the system, withdrawing from the reaction zone a liquid containing allwlation reaction products and lower boiling hydrocarbons suitable as'reactants for the alkylation reaction, treating the liquid thus withdrawn from the reaction zone to separate therefrom a fraction containing the alkylation product and a lower boiling fraction containing hydrocarbons suitable as reactants in the alkylation reaction, and introducing said last-mentioned lower boiling fraction int said reaction zone.

7. A process for alkylating low molecular ing said reaction zone at alkylation conditions of temperature and pressure effective to vaporize unreacted hydrocarbons includingpropane to facilitate maintaining the reactants in the reaction zone at the desired temperature, withdrawing said vaporized hydrocarbons from said rcaction zone, cooling said vaporized hydrocarbons externally of saidv reaction zone to condense at least a portion thereof, reintroducing into said reaction zone as condensate a portion of said cooled hydrocarbons, introducing another portion of said cooled hydrocarbons into a yfractionating zone, maintaining conditions in said fractionating zone effective to separate a condensate fractioncontaining the isobutane introduced into said fractionatingzone and a vapor fraction containing propane, introducing said condensate fraction into said reaction zone, withdrawing said vapor fraction from the system, withdrawing from said reaction zone a hydrocarbon mixture containing alkylation reaction product, normal butane and isobutane, fractionating the lastmentioned hydrocarbon mixture to separate therefrom a low-boiling hydrocarbon fraction predominating in isobutane, and introducing said last-'mentioned fraction into said reaction zone. 8. A A process for alkylating low molecular weight paraflinic hydrocarbons rwith low molecular Weight olenic hydrocarbons to form parailnic hydrocarbons which comprises introducing into an alkylation reaction'zone sulfuric acid alkylation catalyst and a fresh feed comprising isobutane, normal butane, propane and butenes, maintaining said reaction zone at alkylation conditions of temperature and pressure effective to vaporize unreacted hydrocarbons including propane' to facilitate maintaining the reaction zone at the desired reaction temperature, withdrawing said vaporized hydrocarbons from said reaction zone, cooling said vaporized hydrocarbons externally of said reaction zone to condense at least a, portion thereof, reintroducing into said reaction zone as condensate a portion of said cooled hydrocarbons, introducing another portion of said cooled hydrocarbons into a fractionating zone, fractionating the hydrocarbons introduced into said fractionating zone into a -condensate fraction containing substantially all 'the isobutane introduced into said fractionating zone and a vapor fraction containing propane and substantially free from isobutane, introducing said condensate fraction into said reaction zone, and withdrawing said vapor fraction at a rate effective to withdraw from the system propane in an amount equivalent to thenamount of propane introduced into the system as part of the fresh feed. ,Y

9. A process for alkylating low molecular weight parainic hydrocarbons with low molecularweight olefinic hydrocarbons to form paraillnic hydrocarbons which comprises introducing a freshd feed comprising isobutane, normal butane, propane and butenes into a fractionating zone, fractionating hydrocarbons-introduced into said fractionating zone to separate a condensate fraction containing propane and substantially all the isobutane introduced into said'fractionating zone and a vapor fraction containing' propane and substantially free from isobutane, introducing said condensate fraction and sulfuric acid alkylation catalyst into an alkylation reaction zone, maintaining said reaction zone at alkylation conditions of, temperature andv pressure'fe'ffective to vaporize unrea'cted hydrocarbons' including propaneto facilitatemaintaining thereaction zone at the desired reaction temperature, withdrawingsaid vaporized hydrocarbons from said reaction zone, cooling said vaporized' hydrocarbons externally of said reaction zone to ing into said reaction zone as condensate aportionA of said cooled hydrocarbons, introducing ture a hydrocarbon fresh feed comprising said low molecular weight oleilnA hydrocarbons, isobutane and propane, maintaining the liquid mixcondense at least a portion thereof, reintroducanother portion of said cooled hydrocarbons into weight isoparaiiin hydrocarbon with a low molecular weight olefin hydrocarbon in the presence of a liquid acid catalyst to form aVhigher-boiling parafdn hydrocarbon whichgcomprises maintaining 'a liquid body comprising 'an intimate mixture of hydrocarbon reactants an"dacid catalyst and containing said low molecular weight isoparaiiln hydrocarbons in a substantially high ratio to said olefin hydrocarbons, continuously withdraws ing a portion of said liquid mixture containing hydrocarbons; 'continuously charging to saidV liquid mixture hydrocarbon fresh feed comprising said low molecular Weight isoparailin and olefin hydrocarbons and lower-boiling normal parafiin hydrocarbons, maintaining the .liquid mixture at alkylation conditionsof temperature and pressure which permit vaporization oi said unreacted isoparamn hydrocarbons and said lower-boiling normal paraflin hydrocarbons' to facilitate maintaining the liquid mixture at, the desired reaction temperature, withdrawing the vaporized hydrocarbons from said 7liquid mixture, cooling and condensing hydrocarbons thus withdrawn, reintroducing condensate thus obtained into said liquid mixture, fractionating a portion of said vaporized hydrocarbons other than the condensate reintroduced into the liquid mixture to separate said last-mentioned portion of said vaporized hydrocarbons into a condensate containing isoparailln hydrocarbons and avapor ture at alkylation conditions of temperature and pressure which permit vaporization of :propane 'and unreactcd isobutane to `facilitate maintaining the -liquid mixture at the. desired reaction temperature, withdrawing the vaporized hydrocarbons from said liquid mixture, cooling and condensing hydrocarbons thus withdrawn, rein-4 troducing condensate thus obtained into said ,liquid mixture, fractionating a portion of said vaporized hydrocarbons other than vthe condensate reintroduced into the liquid mixture to separate said last-mentioned portion of said vaporv ized hydrocarbons into a condensate containing isobutaneand a vapor containing propane, introducing said last-mentioned condensate into said liquid mixture. and withdrawing said last-mentioned` vapor from the operation.

l2. A process for alkylating a` low molecular weight isoparailin hydrocarbon with-a low molecular weight olefin hydrocarbon in the presence'y of a liquid acid catalyst to form a higher-boiling parafiin hydrocarbon which comprises maintaining a liquid body comprising an intimate mixture of hydrocarbon reactants and acid catalystA and containing said low molecular weight isoparailln hydrocarbon in a substantially-high ratio to said oleiin hydrocarbons, continuously withdrawing a portion of said liquid mixture containing hydrocarbons, continuously chargi g to said liquid mixture a hydrocarbon iresV feed comprising?y said low molecular weightolein and isoparaiiln hydrocarbons and lower-boiling normal paraffin hydrocarbons, maintaining the liquid mixture at alkylationI conditions of temperature and pressure which permit vaporization of unreacted isoparailln hydrocarbons and said lower-boilingJ normal parailin hydrocarbons to facilitate maintaining the liquid mixtureI at the desired reaction temperature, withdrawing the vaporized hydrocarbons from said liquid mixture, cooling and containing said lower-boiling normal parafnn hydrocarbons, reintroducing said last-:mentioned condensate into said liquid mixture, and withdrawing said last-mentionedvapor. from the operation.

11. A process for alkylating isobutane with a low molecular weight oleiln hydrocarbon in the presence of a -liquid acid catalyst to form a higher-boiling paramn hydrocarbon which com prises maintaining a liquid body comprising an condensing hydrocarbons thus removed, reintroducing condensate thus obtained into said liquid mixture, fractionating a portionoifsaid vaporized hydrocarbons other than the condensate reintroduced into the liquid mixture to separate lsaid last-mentioned portion of said. vaporized hydrocarbons into a condensate containing substantially all the isoparaiiin hydrocarbons and a portion of the said lower-boiling normal paraffin hydrocarbons contained therein' and a 'vapor consisting/ot said lower-boiling normal paramn hydrocarbons, said ylast-mentioned vapor being equivalent in quantity to thesaid lower-boiling paramn hydrocarbons introduced into said liquid mixture as fresh feed, reintroducing said lastmentioned condensate into said liquid mixture. and withdrawing said last-mentioned vapor from the system.`

BERNARDUS 

